Originally Posted by
Altima of the Gates
How would he have killed Zouken when we know his soul's vessel is in Sakura as insurance? That, and Nasu was directly asked and wasn't even that vague about it this time, which was unusual for him. The person didn't even ask him if she would be saved, just if she could live a decent life post other routes, and his only answer was "believe in your dreams". Not a good sign.
There are several points that aren't really addressed, we know the grail is ultimately dismantled 10 years later, but that means her condition doesn't improve and the experimentation continues in those ten years barring the old guy suddenly croaking, but if he was gonna croak 2 years like the last guy was talking about in the post above mine, and the decay was speeding up that rapidly, he would be more desperate, not less.
Also, Shinji's attitude is merely not actively being a douche, he won't tell anything to Rin or Shirou despite his so called innate wanting to change, and Nasu confirmed he was mainly freeing himself from his obsession with magecraft, he will leave and that will be the end of that, but he was never the sticking issue here, only another problem in her life but one that wasn't immediately life threatening. Oddly enough, she is the one being more actively supportive of the two, which is hilariously sad and ironic.
If Gil had killed Zouken in UBW, he wouldn't have answered the questioner as he did.